When using existing social network applications, users need to register user identifications in social network applications to show themselves. All operations, such as adding friend, subscribing, querying user's information and sending private message, are executed on basis of the user identification.
With conventional method, in case user A wants to add user B into friend list, it is necessary that user B tells his user identification orally to user A at first. Then, user A is able to add user B into friend list according to the user identification of user B. Thereby, the conventional method cannot provide enough convenience in operation.